1. Field of the Invention
This invention relates to producing methanethiol from H.sub.2 S and CO. More particularly, this invention relates to producing methanethiol by passing a gas feed comprising a mixture of H.sub.2 S and CO over a catalyst comprising an oxide of a metal selected from the group consisting of V, Nb, Ta and mixture thereof supported on titania, at a temperature of at least about 225.degree. C., for a time sufficient to convert at least a portion of said feed to methanethiol.
2. Background of the Disclosure
Hydrogen sulfide is an unwanted by-product of many refinery processes, being very toxic and having few practical uses. In many cases, H.sub.2 S is disposed of by the Claus Process in which a portion of the H.sub.2 S is oxidized to SO.sub.2. The remaining H.sub.2 S is then reacted with the SO.sub.2 in the presence of a suitable catalyst to produce H.sub.2 O and elemental sulfur. H.sub.2 S can also be reacted with oxygen in the presence of an iron oxide catalyst to form water and elemental sulfur.
Some uses of H.sub.2 S include conversion of mononitro aromatic compounds to amino compounds as disclosed in U.S. Pat. No. 4,326,081. In U.S. Pat. No. 4,235,699, Ratcliffe, et al. disclose forming lower molecular weight products from coal and coal tar using a mixture of CO and H.sub.2 S as a hydrogenating agent. Fukuda, et al. in "Catalytic Activity of Metal Sulfides for the Reaction, H.sub.2 S+CO=H.sub.2 +COS", J. Catalysis 49, p. 379-382 (1977), studied first row transition metal sulfides as catalysts for producing COS and H.sub.2 from mixtures of H.sub.2 S and CO (see also Masayuki, et al., "The Study of Thermochemical Hydrogen Preparation. VI. A Hydrogen-evolving Step Through the H.sub.2 S-CO Cycle", Bull. Chem. Soc. Japan, 51 (1) p. 150-153 [1978]).
More recently, Happel, et al. in U.S. Pat. No. 4,151,191 have disclosed the use of sulfur resistant catalysts for methane production in the presence of H.sub.2 S. This reference discloses producing methane from a feed mixture containing H.sub.2, CO and gaseous sulfur compounds, such as H.sub.2 S, by contacting the feed with a predominantly molybdenum oxide catalyst containing at least one element of lanthanide or actenide groups of elements at a temperature of about at least 300.degree. C. U.S. Pat. No. 3,963,785 discloses the synthesis of aliphatic thiols by reacting H.sub.2 S with olefins or aldehydes in the presence of CS.sub.2. Finally, Kodera, et al. in U.S. Pat. No. 3,856,925 disclose the manufacture of H.sub.2 and COS from mixtures of H.sub.2 S and CO using various Group VB, VIB and VIII metal sulfides as catalysts.